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I'm a Noob, Here's my introduction with scratch build pics.

#1
100_0674.JPG 100_0676.JPG 100_0678.JPG 100_0679.JPG 100_0681.JPG 100_0684.JPG 100_0685.JPG 100_0686.JPG 100_0687.JPG 100_0689.JPG 100_0690.JPG 100_0691.JPG 100_0692.JPG 100_0695.JPG 100_0696.JPG 100_0697.JPG 100_0698.JPG 100_0699.JPG 100_0700.JPG 100_0701.JPG Hey guys. I'm Richard Ellis age 25, current occupation is Army Sniper, been serving since 2006. I just got into this hobby after seeing UAV and Raven RQ-11's being used first hand during my deployment in Afghanistan. I am interesting in the foam board building and eventually be comfortable enough to build my own FPV platform and a cool tactical ground station that I can take to the field with me when I am training to see if the Army will let me use my own equipment. I just started building foam board planes with watching Ed's channel on youtube and then downloaded plans from flitetest guys and built the FT3D, pretty cool plans and were very easy to follow. I still have no Transmitter or reciever yet or anything that is electronic, like I said I am brand new to this hobby, but already searched the past last month on what kind of setup I had in mind. I am going to start out with a simple Transmitter/Reciever "FS-TH9X" from Hobbypartz.com $79. A 3300mah Li-Po, a decent charger. Simple 200mw FPV kit from hobbyking.com and so on.

Heres my first scratch builds: last 8 pics are of my 84inch custom wing for a huge glider i want to build, or I will just put it on my RQ-11 fuselage and extend the boom.
 

Craftydan

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#3
Hey Richard! Welcome!

Well you don't start small!

What kind of wood did you use for your spar? What's your weight up to so far?
 
#5
Hey Craftydan, thanks for the warm welcome. Ya it is a little big. The wood I used I purchased at Lowe's and it was all the way in the back of the store sold in 8'x1-1/4"x1/8", I think it was pine. It is a bit heavy, I have a digital scale and weighed it so its 588grams. So, ya a bit on the heavy side but I wanted a very strong wing with no little to no flex at that size and it feels really tough and sturdy. I will post a new pic of what the project looks like right now.
 
#6
The PVC pipe is 3/4" SCH40, which gives it a 1inch O.D. and fits inside the original design, but at 5' it weighs 488grams. I will definitely have to cut it down and figure out how long it should be in relation to the wing span. I may have to not use the RQ-11 as my fuselage (fiberglass) now realizing how much weight and stress this is putting on it. I will more than likely have to build my own out of foam board. I think I will also put 2 motors on the wing kinda like the FT cruiser design (removable power pod design). I would greatly appreciate any suggestions if anyone has any. 100_0703.JPG 100_0704.JPG 100_0705.JPG 100_0706.JPG 100_0707.JPG 100_0708.JPG 100_0709.JPG 100_0710.JPG 100_0711.JPG
 

Craftydan

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#8
Yeah, I'm still getting used to the old standby materials for a DIY project being on the heavy side. There's tradeoffs for everything, but doesn't mean what you have won't fly!

You're just under 2 1/4 lb with the boom, and likely will hit 3 lb with the motor, servos (9g servos might not cut it), tail feathers, batteries and payload. At 100 W/lb, (good target for an average sport plane, but more can gives better performance) you'll need a 300W power system -- still very doable, but any weight you can save goes to better flying and more payload. Installing two 150-200W motors could work out beautifully, and if you mount them forward of the wing, their weight will help in counterbalancing the tail for good CG. When picking out your motor, I'd lean toward a high torque, low kv motor swinging a huge prop. You're probably not going to get or want this plane to fly fast, so the high speed/small diameter props on a high kv motor won't be as efficient for you.

I think you're right about the fiberglass fuselage. With that much stress spread over that long of a moment arm between the weight of the wing and the length of the boom, one hard landing on the back end of the boom might break the fuse in half.

If you're considering building your own fuselage, have you considered something like a twin boom airframe? the Specter comes to my mind (though there are others). Someone recently put together some build articles on it:

http://flitetest.com/articles/40-swappable-specter-an-ibcrazy-design

Uses two carbon fiber rods (arrow shaft or fishing pole) for the tail booms. Mounting the tail directly to the wing takes advantage of your heavy spar's strength, and would shorten any moment arm between them (less stress). Dunno how cheap/easy it is to find locally, but they can be ordered around 1m lengths w/o much searching. This would cut the overall weight and help with balancing the tail.

Keep us posted on your build!
 
#10
Ya I am doing away with the fiberglass RQ11 and will build a 3" or 4" diameter pvc pipe about 18" long for fuselage. Was thinking of using a t-fitting with 2 bolts and wing nuts to hold down the wing, and take bottom part of t-fitting and go straight through fuselage. I seen end caps for 3 and 4 inch pipe too at lowes that I will use and then drill a 1" hole in center to slide boom through. Also noticed I will need some kind of strut design for the wings, the weakest point is the 2 small 6/32x2" bolts that go right thru the center and creates a rocking left and right problem right now. In the pic, the pipe I am holding I cut to 10" just for now. As far as flex for boom, Even with it being 5ft long it was fairly hard to get it to flex. I did see IBCRAZY video, liked it alot, I just want to build something different then what I have seen on the web. 100_0716.JPG 100_0715.JPG
 
#11
Oh, and Craftydan, thanks for all the info you typed up, I didn't know 100w/lb was a way of figuring out a starting point for deciding how much power one would need when building. This may sound crazy but I was thinking about having 4 3300mah 3s batteries for longer flight times in the future when I get into actually flying and gain experience. So payload will have to be in that range for the batteries, FPV, APM 2.5, Reciever, servos, etc...
 
#13
Here is my basic design. pvcfpvDESIGN.jpg If 4"x18" is overkill for fitting 4 3300mah batteries and etc., I would greatly appreciate a opinion on what I can get away with, thanks everyone that have been helpful so far.
 
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Craftydan

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#16
Different is good, but feel free to copy!

In all fairness, I'm leaning on others experience that's served me well so far -- think most of us are -- but we all branch out in our own ways too!

A neat source of info (if you haven't run across it) is the beginners section over at WattFlyers:

http://www.wattflyer.com/forums/forumdisplay.php?f=7

Their sticky articles cover more than how to fly, but cover lots of other things like repair, power system sizing (where I picked up the 100w/lb RoT), batteries and more. They don't have everything (who does?), but they cover a lot of ground that you can use.

Feel free to browse until your brain hurts, then come on back here and build and hangout with us!
 

Craftydan

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#18
BTW, two comments, take'em or leave'em as you see fit.

1. PVC is HEAVY. Not saying it can't be used, but start weighing pieces and counting up a weight budget. Any weight you put in the airframe takes away from your payload/performance/flight time.

I've heard one person put it, any part that survives a bad crash is overbuilt. I'm not saying build that weak, but you don't have to build too strong.


2. Keep your CG in mind as you design. On a typical straight wing airframe it'll be best around 1/3 the root cord from the leading edge. for more complicated wing shapes, there are calculators available online.

treat this as a balance beam. Any weight*length-to-CG you put on one side, you'll have put the same weight*length on the other. so that pair of 9g servos way out on the tail may need a motor mounted on the front of the wing to counterbalance.

The last thing you want to do is waste precious power by adding a lot of ballast in order to balance your plane. Your layout can be made to balance, but balance will be easier if you think and adjust as you build.
 
#20
yeah, I think the pvc is too heavy as well. LMAO for the comment of it looking like a potato gun, well put. To craftydan, I will most definitely check out that website link you posted. As for now on the project I am going to keep the wing design and throw away everything else. I am leaning more to a twin boom, with twin engine 400w each motor being held inside the power pod swappable design like the ftcruiser. Boom will either be square hollow foam board design or 1/2" poplar. I was bored at work today and was drawing the plans out. It kinda looks like IBCrzy design with a twist. I think with the 84" wing span, one side of wing can have 2.4ghz reciever antenna and the other will have the 5.8ghz transmitter antenna, giving me plenty of effecient space between to not have to worry of interference if I ever go with more powerful system down the road. Basically I am building this plane for a foundation that I can grow on and later upgrade but with some durability and rebuildable components and it has to be able to be disasembled for transport and storage due to moving all the time in the military. Thanks again everyone, this thread is fun and I enjoy working on this and like posting the pictures for everyones input.